Prosthesis intended for the treatment of a natural lumen or tract, in particular an endo-urethral prosthesis

ABSTRACT

A prosthesis intended for the treatment of a natural lumen or tract of a human or animal body through which a flow is effected on either side of a sphincter is disclosed. The prosthesis comprises at least one tubular element, in particular of cylindrical shape which is sufficiently flexible to conform to the natural lumen, but sufficiently rigid to maintain an artificial passage in the lumen, and is intended to be placed in the natural lumen. The wall of the tubular element comprises a relatively smooth and soft biocompatible material, such as silicone rubber, at least in its outer part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. application Ser. No. 10/447,110 filed May29, 2003, which is a Continuation of U.S. application Ser. No.09/899,112 filed Jul. 6, 2001 (now U.S. Pat. No. 6,576,008), which is aContinuation-in-Part of U.S. application Ser. No. 09/032,978 filed Mar.2, 1998 (now U.S. Pat. No. 6,290,666), which is a Division of U.S.application Ser. No. 08/501,140 (now U.S. Pat. No. 5,766,209), which aNational Stage application of PCT/FR/94/00171 filed Feb. 16, 1994. Theentire disclosure of the prior applications is hereby incorporated byreference herein in its entirety.

BACKGROUND

The present invention relates to the treatment of natural lumina ortracts of the human or animal body through which a transit or flow of afluid is effected, in particular a body fluid, either liquid or gaseous,on either side of a sphincter. The urinary, respiratory, digestive, andgynecological tracts constitute natural lumina within the meaning of thepresent invention.

“Treatment” is understood to mean both an intervention of a mechanicaltype, aiming to re-establish a flow which has previously been disturbedor prevented on account of an obstruction or a stenosis of the naturallumen, and also a treatment or intervention with a therapeuticobjective, for example, to control the cicatrization of the wall of thenatural lumen after surgical intervention, or to reduce hyperplasia ofan organ or gland surrounding this same lumen.

The present invention will be introduced, defined and described, by wayof a non-limiting example, with reference to the endo-urethralprostheses which are used in the urethra in connection with the striatedmuscular sphincter.

In accordance with the document FR-A-2 667 783, an endo-urethralprosthesis has been described which consists of a tubular element, ofgeneral cylindrical shape, whose wall comprises a relatively smooth andsoft biocompatible material, for example a silicone rubber, at least inits outer part. This tubular element is sufficiently flexible to conformto the anatomical profile of the urethra and to its movements, butsufficiently rigid, particularly in the radial or diametral direction,to maintain an artificial passage in the urethra. This tubular elementis intended to be placed in the urethra, without passing through thestriated muscular sphincter, in the prostatic segment and/or in any oneof the membranous, bulbar, perineal, and penile segments.

“Tubular element” is understood to mean any element whose outer surfaceis described by a generatrix corresponding to a straight or curved line,or other line, about an axis.

According to the document FR-A-2 667 783, the tubular element issupported in the urethra principally by the elastic bearing of the wallof said element, in radial extension, against the urethral wall, andsecondarily by various notches formed in the wall of the same tubularelement, freeing catches which fasten on the urethral wall, somewhat inthe manner of scales.

In practice, such a prosthesis is not self-stabilizing, for variousreasons:

the elastic bearing of the tubular element is insufficient to support itin position in the urethra, except by providing or obtaining a verysubstantial bearing which is likely to damage the urethral wall, leadingto the patient experiencing pain, and in any case rendering thewithdrawal of the implanted prosthesis difficult or impossible,

the fastening catches, or scales, cooperate with the urethral wall, inits longitudinal direction, only in the sense of precluding or limitingthe descent of the prosthesis; these fastening catches cannot thereforeprevent the prosthesis from ascending,

the externally smooth nature of the tubular element encourages itsnatural sliding against the urethral wall, in particular during thevarious movements of the urethra,

and, finally, the various notches constitute as many punctiform bearingsurfaces, or zones of turbulence, on which both the static pressure andthe dynamic pressure of the urinary flow act during miction; this hasthe result of encouraging the descent of the urethral prosthesis.

In accordance with the document WO91/16005, metal prostheses arefurthermore known which consist of two metal elements, each consistingof metal coils, either contiguous or non-contiguous, which are intendedto be arranged in the urethra on either side, respectively, of thestriated muscular sphincter. For each element, these coils, which arecompressible in a centripetal manner and are expansible in a centrifugalmanner, define, in their expanded position, an enveloping surface with across section varying from one end to the other.

Prostheses are also known which consist of a metallic or non-metallictube which is perforated and is expansible at the moment of itsimplantation in the urethra.

At present, the various urethral prostheses proposed and described havebeen unable to reconcile:

on the one hand, self-stabilization, which presupposes in one way oranother, in the previous solutions, a certain anchoring of theprosthesis on the mucosa of the urethral wall,

and, on the other hand, ease of introduction and especially ofwithdrawal of the prosthesis, that is to say its reversibility.

SUMMARY

The present invention relates to a prosthesis, and in particular anendo-urethral prosthesis, which is self-stabilizing and which can beintroduced and withdrawn in a non-traumatic manner from the naturallumen or tract in which it is implanted.

A prosthesis according to the invention comprises two tubular elementswhich are made from a relatively smooth and soft biocompatible material,such as a silicone rubber, and which are intended to be arranged in thelumen on either side, respectively, of the sphincter, and to be attachedto each other by a flexible and deformable connection means which isintended to be held in the orifice of the sphincter. Each element has anexternal cross section which is substantially constant from one end tothe other of said element.

The connection means preferably consists of a flexible sleeve, the twoends of which are connected, in continuity of flow, to the two tubularelements respectively; this connection means can also be a singleconnecting thread or several connecting threads which are attachedindividually at their two ends to the two tubular elements,respectively.

A prosthesis which comprises the technical characteristics definedhereinabove moreover affords the following decisive advantages.

The “flexible sleeve or connection means constitutes a predeterminedzone of bending of the prosthesis, which is capable of absorbing withoutstiffness all the movements of the natural lumen. This predeterminedzone of bending permits harmonious functioning of the sphincter. Thelength of this flexible sleeve is moreover adapted to that of thesphincter.

Such a prosthesis has a uniform external profile, which fact renders itnon-traumatic, both during its insertion and its removal, whichmaneuvers can be carried out without general anesthesia, and which factmakes it easy to position. This also makes it biocompatible in the sensethat it does not irritate the inner mucosa of the natural lumen ortract.

Such a prosthesis also has an inner surface which is continuous anduniform, in particular as regards its internal cross section, which factconfers upon it very good hydraulic properties, that is to say withoutobstacle, for example, vis-á-vis urinary flow. As far as miction isconcerned, a urethral prosthesis according to the invention is not movedby the urinary flow.

Such a prosthesis is self-stabilizing with respect to the sphincter: atrest, the sphincter immobilizes it, and during miction its sliding isprevented by the two tubular elements which are in abutment,respectively, on either side of the sphincter.

Such a prosthesis is also particularly easy to put into place, usingsimple instruments, in particular without necessarily having recourse toendoscopic or radiological checks. In particular, as is explainedhereinafter, by simply sliding the endo-urethral prosthesis along theurethra, it is immobilized automatically in the correct position at themoment when the flexible sleeve arrives at the level of the sphincterwhich closes over it.

Essentially, such a prosthesis does not impede or disturb the functionsof the sphincter; it opens and closes, and thus functions in asymmetrical and fluid-tight manner, under the action of the sphincter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described with reference to the attacheddrawings, in which:

FIG. 1 represents an endo-urethral prosthesis in accordance with a firstembodiment of the invention;

FIG. 2 represents an anatomical section of the urinary tract of thehuman male; a prosthesis according to FIG. 1 is represented in thissection, in its implanted position;

FIGS. 3 and 4 are diagrammatic representations showing the cooperationof a prosthesis according to the invention and the striated muscularsphincter; FIG. 3 shows the prosthesis in the flow position with thesphincter relaxed; FIG. 4 shows the prosthesis in the closed positionwith the sphincter contracted;

FIG. 5 represents three variants, designated (a) through (c), of aflexible sleeve belonging to a prosthesis according to FIG. 1; eachvariant (a) through (c) is represented respectively in the flow position(miction) and in the closed position (continence) and in cross section;

FIG. 6 represents an endo-urethral prosthesis in accordance with asecond embodiment of the invention;

FIG. 7 represents an endo-urethral prosthesis in accordance with a thirdembodiment of the invention;

FIG. 8 represents an assembly for insertion of a prosthesis according toFIG. 6, this assembly being shown at the top in FIG. 8 b in the positionin which it is detached from the prosthesis, and at the bottom in FIG. 8a in the position in which it is engaged on the prosthesis;

FIGS. 9 through 12 represent, respectively, four successive stages ofthe procedure for insertion of a prosthesis according to FIG. 6; and

FIG. 13 represents a prosthesis in accordance with an embodiment of theinvention;

FIG. 14 illustrates an exemplary embodiment of a prosthetic stentaccording to this invention, in which the flexible connecting element isa thread; and

FIG. 15 illustrates an exemplary embodiment of a prosthetic stentaccording to this invention, in which the flexible connecting element isa plurality of threads.

DETAILED DESCRIPTION OF EMBODIMENTS

In accordance with FIG. 2, the urethra 1 extends upwards from the meatusurinarius 7 as far as the neck 3 of the bladder 2. Above the striatedmuscular sphincter 5, the urethra comprises a super-collicular prostaticsegment 101 and a sub-collicular prostatic segment 102 on either side ofthe verumontanum. Below the sphincter 5, the urethra comprises, towardthe meatus 7, the membranous segment 103, the bulbar segment 104, theperineal segment 105, and, finally, the penile segment 106.

A prosthesis 8 according to the invention, such as is represented inFIG. 1, is intended to be implanted, as will be described hereinafter,in the urethra 1 on either side of the sphincter 5.

Ex vivo, that is to say in its non-implanted state, as represented inFIG. 1, a prosthesis 8 according to the invention comprises two tubularelements 9 and 11, of cylindrical shape in the representation in FIG. 1,the wall of which consists of a relatively smooth and soft biocompatibleand optionally biodegradable material, for example a silicone rubber.Each tubular element 9 or 11 is sufficiently flexible to conform to thesegment of the urethra in which it is to be placed, while at the sametime being sufficiently rigid to maintain an artificial endo-urethralpassage. Each tubular element 9 or 11 has an external cross sectionwhich is substantially constant from one end to the other of saidelement. These two tubular elements are connected or attached to eachother by a connection means which consists, according to the embodimentsin FIGS. 1, 6, 7, and 13, of a flexible sleeve 10 which is intended tobe held in the orifice of the sphincter 5, as shown, once implanted, inFIG. 2.

As is represented in FIG. 2, once put into place, as is describedhereinafter, the prosthesis thus comprises, in a continuous manner, thetwo tubular elements 9 and 11 which are arranged in the urethra 1 oneither side, respectively, of the sphincter 5 and are attached to eachother via the flexible sleeve 10 which is held in the orifice of thesphincter 5.

As is shown in FIG. 1, the two ends of the flexible sleeve 10 areconnected, in continuity of flow, to the two tubular elements 9 and 11,respectively. The wall of the sleeve 10 is more flexible, and inparticular thinner, than the wall of each tubular element 9 or 11. Inpractice, this wall of the sleeve 10 can be made from a web of silicone,the tubular elements 9 and 11 for their part consisting of a wall ofsilicone rubber which is thicker by comparison. The join between thesleeve 10 on the one hand and the two tubular elements 9 and 11 isobtained in any suitable manner, for example by adhesive bonding. As isrepresented in FIG. 5, the flexible sleeve 10 can be perforated aboutits circumference, in particular by longitudinal slots or windows, insuch a way as to facilitate the bending of the sleeve 10 and to ensurecontinence; the dimensions of these windows or slots are such that thejoin between the tubular elements 9 and 11 is reduced to a bundle ofstrips or threads forming a continuation of said tubular elements 9 and11.

As is shown diagrammatically in FIGS. 3 and 4, the wall of the flexiblesleeve 10 is capable of assuming two configurations under the action ofthe striated muscular sphincter 5, namely a flow configurationrepresented in FIG. 3, having the shape of a cylinder, upon relaxationof the sphincter 5, and a closed configuration, represented in FIG. 4,corresponding to a biconical or hourglass shape, upon contraction of thesphincter 5.

As is represented in FIG. 3, but also in its ex vivo configuration, thetubular elements 9 and 11 form, together with the flexible sleeve 10, aconduit having an internal cross section which is substantially constantin the longitudinal direction of the prosthesis 8. Each tubular element9 or 11 has an external profile which is substantially constant oruniform in the same longitudinal direction. Irrespective of theconfiguration, the two ends of the flexible sleeve 10 are connected inflow continuity to the two tubular elements 9 and 11, respectively. Thisbeing the case, it is possible, in a manner not shown, and when thecaliber of the urethral meatus allows it, for the lower tubular element11 to have an external cross section greater than that of the uppertubular element 9, for the purpose of promoting self-stabilizing and ofpreventing upward migration of the prosthesis.

As is represented in FIG. 1, ex vivo, that is to say free of any stressimposed by its implantation in the urethra, each tubular element 9 or 11can have a predetermined and adapted angulation, along its axis,identical to or different than the natural or physiological angulationof the segment in which said tubular element is intended to beimplanted. More specifically, taking into consideration the directionand orientation of implantation according to FIG. 2, the upper tubularsegment 9 can have an angulation of between 140 and 160°, and preferablyone equal to 150°, and the lower tubular segment 11 can have anangulation of between 110 and 130°, and preferably one equal to 120°.This angulation is remanent, which means that under stress it can besuppressed, but that, when there is no stress, each tubular elementessentially recovers, in an elastic manner, its original angulation. Theangulation used, for example that of the lower tubular element 11 in itspart adjacent to the sleeve 10 facing the sphincter 5, can be chosen tocontrast with the anatomical shape of the urethra, for example of thebulbar segment 104, and thus to counter the upward migration of theprosthesis through the sphincter 5.

The external diameter of the two tubular elements is about 7.3 mm (22 inaccordance with the Charriére scale); it can be 8 mm (Charriére 24) forthe lower tubular element.

As is shown in FIG. 1, the prosthesis 8 comprises a removal thread 14 atits lower end 15, still in the direction of implantation represented inFIG. 2.

In accordance with the embodiment represented in FIG. 13, each tubularelement 9 or 11 can be perforated, with perforations 51 distributedalong its length at the side near its free end, that is to say oppositethe sleeve 10; these perforations promote the embedding of theprosthesis with respect to the urethral wall.

In accordance with the embodiment represented in FIG. 7, the uppertubular element 9 has one or more notches distributed along its length,for example a helical notch 9 a, in the manner of a screw thread, ornotches in a staggered arrangement, and this is again to promote theelimination of the natural secretions of the prostate or tissue debrisfreed by treatment thereof.

As is shown in FIG. 13, a metallic or non-metallic coil 52 constitutes areinforcement for each tubular element 9 or 11. It is embedded in theelastomeric material of the tube of each tubular element, as isrepresented in FIG. 13, but it can also be externally exposed, forexample for the purpose of therapeutic treatment of the urethral wall.The reinforcement 52 of each tubular element 9 or 11 extends from thesleeve 10 over only a part of the length of said tubular element, insuch a way that the remaining part can be cut, for example in order toadapt the length of the tubular element 9 to that of the prostaticsegment 101/102, or to adapt the length of the tubular element 11 withrespect to the site of a stenosis in that portion of the urethra 1 belowthe sphincter 5.

As is shown in FIG. 13, the elastomeric material covers the metallicreinforcement 52, at least toward the outside, and thus constitutes atleast the external part of each tubular element 9 or 11 in contact withthe urethral wall.

In accordance with FIGS. 6 and 7, the upper end of the upper tubularelement 9, that is to say the end opposite the connection sleeve 10, isclosed transversely and is presented in the form of a convex and roundedstump 9 b. This stump has one or two lateral orifices 9 c forcommunicating with the inside of the tubular element 9.

Each tubular element 9 or 11 can be coated on its outer surface with atherapeutic substance for the purpose of treating the urethra.

In accordance with FIG. 8 b, in order to insert a urethral prosthesis inaccordance with FIG. 6 or FIG. 7, an assembly is used which comprises:

a semi-rigid and hollow mandrel 60 whose external cross section isadapted to receive the prosthesis 8 which is engaged onto it; thismandrel has, at one extremity, a conical outer limit stop 61, and, atthe other extremity, a sealed end 62 against which the closed end 9 b ofthe prosthesis 8 comes into abutment in its engaged position; thissealed end 62 of the mandrel 60 has an eyelet 62 a for flow inside themandrel 60, which eyelet 62 a can be brought into line with the lateralorifice 9 c of the prosthesis, again in its engaged position;

a rigid and hollow pusher 63 whose internal cross section is adapted forengagement of said pusher on the semi-rigid mandrel 60; the length ofthe pusher 63 is adapted to act, in its engaged position, as a spacerbetween the engaged prosthesis 8 and the outer limit stop 61 of themandrel 60.

The insertion device previously described is used in the followingmanner.

A single component is formed from:

the mandrel 60;

the pusher 63, engaged on the mandrel 60, and coming into abutmentagainst its proximal end, formed by the conical limit stop 61;

and, finally, the prosthesis 8 which is also engaged on the free end ofthe mandrel 60 so as to come into abutment via its end 9 b against thefree end 62 of the mandrel 60.

In this assembled position, represented at the bottom in FIG. 8 a, thepusher 63 acts as a spacer between the prosthesis 8 and the outer limitstop 61 of the mandrel 60. The prosthesis 8 is oriented angularly withrespect to the mandrel 60, in such a way that the flow eyelet 62 a is inline with the lateral orifice 9 c of the prosthesis, of greater crosssection.

Following lubrication of the duct 1 of the urethra, the assembly whichhas been formed is inserted through the urethral meatus 7 until theupper end 9 b of the prosthesis opens into the bladder 2. From thismoment, the flow of urine through the mandrel 60 indicates that theinsertion device has arrived in the bladder, in accordance with theposition represented in FIG. 9.

The mandrel 60 is then released and withdrawn, while at the same timekeeping the pusher 63 in position in the urethra in such a way that theprosthesis 8 does not move; compare FIG. 10.

Once the mandrel 60 has been withdrawn, the pusher 63 is itselfwithdrawn from the urethra 1; compare FIG. 11. At this stage, the lowertubular element 11 of the prosthesis 8 is situated level with thestriated muscular sphincter.

A gentle downward pull, exerted via the thread 14, makes it possible toslide the lower tubular element 11 and to engage the flexible sleeve 10in the sphincter.

At this moment, the operating surgeon immediately experiences a blockingeffect on withdrawal, which corresponds to the correct positioning ofthe prosthesis 8 with respect to the sphincter 5 which closes on theflexible sleeve 10. The correct position of the prosthesis is thus foundautomatically; compare FIG. 12.

During this last operation, the operating surgeon can also use his/herindex finger to perform rectal touch exploration since the lower tubularelement 11 is clearly felt by the finger, and its passage this side ofthe sphincter 5 is clearly noted, with the disappearance of the firmnessof said lower tubular element, replaced by the flexible sleeve 10. Thecorrect positioning of the prosthesis 8 with respect to the sphincter 5is completely painless, and it does not necessitate the use of any rigidinstruments, for example forceps. Nor does it necessitate anyradiological checks. At the very most, it may be facilitated by the useof an echography probe, which replaces the finger in the rectum.

From FIG. 12, the prosthesis in place can be easily withdrawn, usingforceps for example, by simply pulling on the free edge of the lowertubular element 11; the resistance of the sphincter 5 is low since theclosure pressure of the latter is less than the pressure exerted by a100 cm water column. As the upper element 9 is engaged in the sphincter5, the sliding and withdrawal of the prosthesis 8 are effected withoutthem catching at all on the urethral wall.

A prosthesis in accordance with FIG. 6, put into place with an insertiondevice according to FIG. 8, is at one and the same time non-traumatic,positioned in a quasi-automatic manner with respect to the sphincter,and self-stabilizing.

This prosthesis is non-traumatic both by virtue of its externalconfiguration and by virtue of its handling:

its configuration is non-traumatic on account of its convex or rounded,and optionally flexible, upper end 9 b, which prevents any traumatism ofthe urethral mucosa, and thus any bleeding, on account of its virtuallysmooth external surface, that is to say without any specific rougheningor reliefs, and on account of the flexible intermediate sleeve,permitting the normal action of the sphincter;

its handling is non-traumatic since, as has been described above, itspositioning is as gentle and straightforward as that of an indwellingcatheter; by permitting the normal functioning of the sphincter, theprosthesis is presented in the manner of an indwelling continencecatheter; throughout the period during which the patient is providedwith this prosthesis, the bladder is not injured, which fact preventsany formation of clots; and at the moment of its withdrawal, theprosthesis 8 slides out as a single piece without causing the patientany particular pain.

The positioning of a prosthesis according to the invention is quasiautomatic since in the final analysis it is effected by means of simpletactile perception of a resistance at the moment when the sphinctercloses on the flexible sleeve 10. According to the invention, thepositioning is based on tactile locating, both by the traction exertedon the thread 14, and/or by a rectal touch exploration by which it ispossible to detect the completion of the passage of the lower tubularelement 11 through the sphincter 5. And, according to the invention, anyerror in positioning can be rectified by moving the prosthesis by meansof a slight traction which causes the patient little pain and which forthis reason does not necessitate general anesthesia.

And, the prosthesis is self-stabilizing by virtue of the presence of thetwo tubular elements 9 and 11 on either side of the sphincter 5. Thisself-stabilizing can furthermore be improved by the presence of orificesor notches, as described in FIGS. 7 and 13, in which the urethral mucosaengages.

FIG. 14 illustrates an exemplary embodiment of a prosthesis intended tobe implanted in the urethra on either side of the sphincter. Ex vivo,that is to say in its non-implanted state, the prosthesis comprises twoelements 2 and 3. These two elements are connected or attached to eachother by a thread 30, which is intended to be held in the orifice

FIG. 15 illustrates an exemplary embodiment of a prosthesis intended tobe implanted in the urethra on either side of the sphincter. As with theprosthesis of FIG. 14, the prosthesis of FIG. 15 comprises two elements2 and 3. However, in this embodiment, these two elements are connectedor attached by a plurality of threads 30.

1. A prosthesis capable of being inserted in a biological lumen ortract, comprising: first and second elements that are locatable onrespective distal and proximal sides of a sphincter surrounding thelumen or tract, wherein the first element is sufficiently flexible to atleast partially conform to the lumen or tract and sufficiently rigid tomaintain a passage through the lumen or tract, and wherein the secondelement comprises a surface that abuts the proximal side of thesphincter; and a connecting element interconnecting the first elementand the second element, wherein the connecting element comprises amiddle portion locatable in the sphincter that is deformable in responseto pressure by the sphincter to allow the sphincter to close naturallyand thereby close the lumen or tract to natural fluid flows.
 2. Theprosthesis of claim 1, wherein the lumen or tract is the human maleurethra.
 3. The prosthesis of claim 2, wherein the first element istubular and traverses at least a portion of a segment of the maleurethra extending between the bladder and the distal side of thesphincter.
 4. The prosthesis of claim 3, wherein the tubular elementcomprises a distal end and proximal end, and the distal end resides atleast partially within the bladder when placed in the male urethra. 5.The prosthesis of claim 4, wherein a tip of the distal end of thetubular element is closed and has a convex shape.
 6. The prosthesis ofclaim 5, wherein the proximal end of the tubular element comprises aproximal end opening, the distal end of the tubular element along asurface residing within the bladder comprises a side opening, and alumen extends within the tubular element providing fluid communicationbetween the proximal end opening and the side opening.
 7. The prosthesisof claim 1, wherein one or both of the first and second elementscomprises silicone rubber.
 8. The prosthesis of claim 1, wherein thesecond element comprises a cross-sectional diameter along at least aportion of the second element that is larger than a cross-sectionaldiameter along at least a portion of the first element.
 9. Theprosthesis of claim 4, wherein the second element comprises across-sectional diameter along at least a portion of the second elementthat is larger than a cross-sectional diameter along at least a portionof the tubular element.
 10. The prosthesis of claim 9, wherein thesecond element comprises an angulated exterior surface that extendsalong a longitudinal axis of the lumen.
 11. The prosthesis of claim 3,wherein the abutting surface counters upward migration of the tubularsegment further into the bladder once the prosthesis is deployed. 12.The prosthesis of claim 3, wherein the second element is locatablewithin a bulbar urethral segment extending from the proximal side of thesphincter.
 13. The prosthesis of claim 12, wherein the second elementcomprises a surface that conforms to a surface of the bulbar urethralsegment.
 14. A method of treating an obstruction of a male urethra,comprising: supporting said male urethra at a site of said obstructionwith the prosthesis of claim 1 by inserting said prosthesis into saidmale urethra so that said first element supports said male urethra atsaid site of said obstruction.
 15. A prosthesis capable of beinginserted in a biological lumen or tract, comprising: first and secondelements that are locatable on either side of a sphincter surroundingthe lumen or tract, wherein at least one of said first and secondelements is sufficiently flexible to conform to the lumen or tract andsufficiently rigid to maintain a passage through the lumen or tractagainst a force that tends to obstruct the lumen or tract; and aconnecting element comprising at least one thread, wherein the threadtraverses the sphincter and interconnects the first and second elements.16. The prosthesis of claim 15, wherein abutment of the second elementagainst the sphincter can inhibit upward migration of the first element.17. The prosthesis of claim 15, wherein said connecting elementcomprises a plurality of threads.
 18. A method of treating anobstruction of a male urethra, comprising: supporting said male urethraat a site of said obstruction with the prosthesis of claim 15 byinserting said prosthesis into said male urethra so that said firstelement supports said male urethra at said site of said obstruction. 19.A prosthesis for implanting in a lumen, comprising a first tubularelement, a second element, and a connecting element, said connectingelement comprising a plurality of threads, wherein the first and secondelements are locatable on either side of a sphincter surrounding thelumen and the plurality of threads traverse the sphincter andinterconnect said first and second elements.
 20. A method of treating anobstruction of a male urethra, comprising: supporting said male urethraat a site of said obstruction with the prosthesis of claim 19 byinserting said prosthesis into said male urethra so that said firstelement supports said male urethra at said site of said obstruction. 21.An intraurethral device, comprising: (i) a first tubular elementcomprising a flexible, biocompatible material, and comprising a proximalportion and a distal portion, and a central portion with a substantiallyconstant outer diameter, wherein said proximal portion comprises an endopening to allow passage of fluid and said distal portion comprises anopening to allow urine to enter said first tubular element from thebladder; (ii) a second element comprising a flexible, biocompatiblematerial, and comprising a proximal end and a distal end, wherein awidth dimension along at least a portion of the second element isgreater than the outer diameter of the central portion of the firsttubular element; and (iii) a connecting element comprising at least onethread connecting said proximal portion of said first element to saiddistal end of said second element.
 22. A method of treating anobstruction of a male urethra, comprising: supporting said male urethraat a site of said obstruction with the prosthesis of claim 21 byinserting said prosthesis into said male urethra so that said firstelement supports said male urethra at said site of said obstruction.